1. Field of the Invention
The present invention relates to novel copolyesteramides having a random or alternately regularly recurring block structure, and which have a high molecular weight and significant flexibility and elasticity down to temperatures which are below or equal to -30.degree. C.
2. Description of the Prior Art
Copolyesteramides having glass transition temperatures below 0.degree. C. have already been described in the literature. For example, U.S. Pat. No. 3,650,999 notes block copolyesteramides, the crystalline phase of which consists of polyester units and the amorphous phase consisting of polyamide units. However, copolymers of this type lose all flexibility and pliability at between -10.degree. C. and -20.degree. C. Furthermore, their relatively low molecular weight only enables them to be used as adhesives.
Likewise, French Pat. No. 77/22,305 describes thermoplastic elastomers consisting of block copolyesteramides. These polymers possess valuable properties, in particular flexibility at low temperature. However, their moduli are not generally sufficiently low and their heterogeneity in molten state makes them difficult to prepare.
Thus, for certain applications, serious need exists in this art for thermoplastic elastomers which have good cohesion while at the same time remain pliable down to temperatures below -30.degree. C.